The purpose of the Clinical Core is to provide biological specimens and behavioral data to the individual research projects. This core will be located in Indianapolis. Core research personnel will enroll and maintain the cohort of adolescent female research subjects over the five year duration of the center, collect all required biological samples (genitourinary swabs, endocervical swabs, vaginal lavages, urine, cervical biopsies, and blood), behavioral information (self-administered questionnaires and personal interviews), and provide interim reproductive health examinations and data collection to facilitate subject retention. The research staff will also be responsible for locating recruiting, enrolling and providing necessary treatment for STI to partners. Research personnel will include the principal investigator of the core, clinical research coordinator, research nurse practitioner, and one Disease Intervention Speciatist (DIS) from the Marion County Health Department. The research nurse will obtain all biological specimens and provide treatment for STI. DIS will perform two important fieldwork functions: (1) contact partners of subjects to obtain personal information, urine samples, provide appropriate antibiotic treatment when partners of infected women prefer to be treated outside of the Marion County STD Clinic (Bell Flower); (2) weekly contact with all subjects during the three month periods of intense data collection to obtain self-directed vaginal swabs, personal behavioral diaries and interview information. Weekly research meetings to assure sucessful completion of project activities will include all personnel of clinical, laboratory and biostatistics cores and principal investigators.